As technology progresses, processes tend to proceed at a faster pace. Most processes require the coordination of a number of components, and the process can only proceed as fast as the slowest component allows unless multiple like components are used. There are certain processes in which the weight of an article is required, but to date no scale has been available that provides accurate, fast weighing. By accurate is meant the ability to weigh an object having a weight of up to 32 ounces within 1/32 of an ounce. By fast is meant the ability to weigh a stream of conveyed articles within less than one second per article. A process where there is a need for fast weighing is in the processing of mail. High speed systems have been developed whereby the appropriate number of inserts, which number may vary from envelope to envelope, are placed within an envelope. The envelope is sealed and postage is printed on the envelope. Before the postage can be printed, however, it is necessary that the weight of the mail piece be determined. Heretofore, weighing devices for such mail processing systems have been developed, but these generally have been rather slow. Actually, many prior weighing devices combined a standard scale with a mechanism that would stop the mail to allow weighing to take place. In order to accommodate the output of an inserter, multiple scales would be used with alternate mail pieces diverted to such scales.
Although these prior weighing devices work rather well with prior mail processing systems, with high speed inserters of contemporary design, the one function that inhibits fast, processing of mail is the weighing of mail pieces before postage is applied thereto. In order to overcome this problem, multiple scales would be used downstream from a high speed inserter and the mail pieces would be alternated to such scales. Obviously, use of multiple scales is expensive and requires additional conveying functions that could result in a greater number of jams.
Much effort has been expanded in trying to develop a weighing scale that meets the heretofore enumerated goals. One such weighing scale is described in co-pending patent application entitled APPARATUS AND METHOD OF DETERMINING THE MASS OF AN ARTICLE BY MEASURING THE SHIFT IN THE PERIOD OF HARMONIC MOTION filed July 13, 1987 and having Ser. No. 073,790. This weighing scale, as well as others of this type, require a conveying mechanism that will place articles onto the pan of the weighing scale quickly, hold the article securely while weighing takes place and removes the article rapidly following weighing.